17 May 2012

Harrison's Ch. 80: "Involuntary Weight Loss"

Perhaps you watched the film "Julie and Julia" a few years ago. It is partly about a blogger, Julie Powell, who spent a year making every recipe in Julia Child's best-known cookbook.

I am doing something similar (albeit less tasty and less likely to be made into a feature film starring Meryl Streep). I am in the process of reading Harrison's Principles of Internal Medicine in its entirety. Harrison's is a dense, 3,600-page, two-volume tome that is the closest thing to a bible in clinical medicine. I am reflecting upon some of its chapters during the year or so it takes me to finish. 

From Ch. 80 ("Involuntary Weight Loss"): 
Involuntary weight loss (IWL) is frequently insidious and can have important implications, often serving as a harbinger of serious underlying disease. Clinically important weight loss is defined as the loss of 10 pounds (4.5 kg) or >5% of one's body weight over a period of 6–12 months. IWL is encountered in up to 8% of all adult outpatients and 27% of frail persons age 65 years and older. There is no identifiable cause in up to one-quarter of patients despite extensive investigation....Weight loss in older persons is associated with a variety of deleterious effects, including hip fracture, pressure ulcers, impaired immune function, decreased functional status, and death. Not surprisingly, significant weight loss is associated with increased mortality, which can range from 9% to as high as 38% within 1 to 2.5 years in the absence of clinical awareness and attention.

The patient seemed healthy enough. In her 60s, she had stopped smoking 10 years ago and loved doing aerobics. She was getting over a cold. Although she was being treated for hypertension, her blood pressure now was substantially below 120/80 (i.e. her blood pressure was not high).

The doctor asked her how she had managed to get her blood pressure so dramatically in check. "I've lost a lot of weight," she beamed. "I used to be overweight, but now I've really slimmed down."

"How did you manage that?"

"I dunno. Recently I haven't had much of an appetite." The doctor and I looked at the chart, and the woman had lost about 20% of her body weight over the past year. She had been slightly overweight before and her weight now was the low end of normal.

Upon seeing the numbers the doctor and I shuddered almost imperceptibly. While the patient thought her weight loss was good news, we felt the opposite. We now had to order a variety of lab tests and a chest X-ray, checking in particular for cancer. The doctor cautioned that if this initial battery of tests came back clean, he would have to order yet another panel of tests and imaging studies.

Lots of things can cause weight loss in the elderly, some of them deadly and some of them not. How hard should we be looking for the underlying cause? If we ordered every medical test known to man, we still might not have a clue of what was causing the weight loss.

Part of the art of medicine is deciding how far to pursue leads. How long should a doctor take the patient's history? How many tests should we order? How extensive should a surgery be? There are no clear answers, and part of the burden and challenge of being a medical provider is that it falls to them to make these impossible judgment calls.